A flat-field soft X-ray spectrometer for X-ray absorption spectroscopy measurement of warm dense matter

Abstract

A flat-field soft X-ray spectrometer operating in the spectral range of 250-1240 eV was designed and built for warm dense matter and high-energy density plasma physics. It employs a grazing incidence toroidal mirror as a focusing optic, an aberration-corrected varied line-spacing concave grating with 2400 lines/mm as a dispersive element, and a charge coupled device as an X-ray detector. The dispersion and energy resolution are calibrated with a high-power laser-produced plasma and X-ray free electron laser sources. A resolving power over 370 was achieved over the entire spectral range. A super broadband spectrum in the range of 250-1000 eV was measured from the laser-produced bismuth plasma. The signal-to-noise ratio of 130 was obtained with an average of 10 pulses. These results demonstrate the capability of the spectrometer for single laser shot based experiments for warm dense matter and high energy density plasma research.